Meeting Abstract

P1.134  Jan. 4  A Phylogenetic Analysis of Sexual Size Dimorphism in Turtles GOSNELL, J.S.*; RIVERA, G.; BLOB, R.W.; Clemson University; Clemson University; Clemson University stephengosnell@msn.com

Sexual size dimorphism (SSD) is widespread in a variety of vertebrate taxa, and its presence has been associated with a wide range of evolutionary and ecological factors. Turtles, as a lineage, have been shown to include species that exhibit each of the varieties of SSD (male-biased or female-biased), as well as species without SSD. To provide a framework for evaluations of potential correlates with the presence and direction of SSD in turtles, we examined the phylogenetic distribution of SSD in this clade. Phylogenies were compiled from multiple published sources to develop a phylogeny that included all species studied (> 100 species). Additional data derived from published sources for each species included the direction and magnitude of SSD, plastron and carapace length, and preferred habitat (terrestrial vs non-terrestrial). The phylogenetic distribution of SSD was then evaluated using parsimony-based methods. These analyses indicated that the ancestral condition for turtles was for females to be larger than males. Male-biased SSD evolved independently multiple times in turtles, but the state of SSD was not closely associated with environment.